I have an iPhone and the colors are very true when they make it into my computer. I've found that taking the pic at approximately 12-14 inches makes the pattern the correct size in my quilt. However, I must say this is a guess. I didn't actually have someone measure the height I'm holding my camera.
I've also noticed that with certain colors it wasn't satisfactory. I was trying to photo a light yellow and all I got was a muddled yellowing grey. It could have been my lighting though, because it was a dreary day and I was taking it using natural lighting in my quilt room. What I did there was go to the site where the yellow was and copied a pic of it into EQ7. That worked fine for what I was doing.